You can deactivate even now and avail free time without a hassle to remember to cancel.

You will get this massage ” “You’ve cancelled your Skype Premium with Unlimited World subscription. You can continue to make calls until it expires on April 6, 2013.
No further payments will be taken unless you reactivate this subscription.”

It is not a scam. They way it works is that you need to cancel the subscription after 27 days else they will deduct the next month’s charge. They do this because many people forget to cancel and these people get easy money. One must just keep a reminder to cancel the subscription at the end of 27 days,